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Page 12 of 32 Keum et al. Soft Sci 2024;4:34 https://dx.doi.org/10.20517/ss.2024.26

Table 2. Comparison of stretchability, carrier mobility, SS, active materials, and the applications of stretchable TFTs
Mobility
2
-1
(cm ·V ·s On/Off Active materials
-1
Year Type Stretchability ) ratio (Channel layer) Applications Ref.
SS
-1
(mV·dec )
2021 Intrinsically stretchable 100% 1.81 N/A PIDTBT Stretchable OTFTs [64]
OTFT N/A
2022 Intrinsically stretchable 620% 0.6 1.0 × 10 5 PDPP-TT Stretchable amplifier [68]
OTFT 500 circuits
2022 Intrinsically stretchable 25% 1 4.5 × 10 4 PDPP-C4Ph Stretchable OTFTs [66]
OTFT N/A
2022 Intrinsically stretchable 120% 1.28 N/A PU(DPP)/PDPP3T Stretchable OTFTs [67]
OTFT N/A
2021 Intrinsically stretchable 50% 1 N/A In-situ rubber matrix Stretchable OTFTs [65]
OTFT N/A semiconductor
2023 Low-dimensional 40% 12.52 2.31 × CNTs Logic gate circuits [85]
channel 252 10 5
5
2021 Low-dimensional 100% 24 1.1 × 10 CNTs Stretchable CNT-TFTs [82]
channel > 1,000
8
2021 Low-dimensional 50% 32.4 1.0 × 10 MoS Optoelectronics [84]
2
channel N/A
7
2024 Rigid island structure 50% 12.7 1.0 × 10 IGZO Logic gate circuits [80]
117
2022 Serpentine string 100% 56.2 N/A ITO Stretchable large-scale [78]
structure N/A integration
8
2022 Rigid island structure 50% 30 1.0 × 10 ITZO Stretchable metal-oxide TFT [77]
N/A
SS: Subthreshold swing; TFT: thin-film transistor; OTFT: organic thin film transistor; N/A: not available; PIDTBT: indacenodithiophene-co-
benzothiadiazole; PDPP-TT: poly(3,6-di(2-thien-5-yl)-2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]pyrrole-1,4-dione) with thieno[3,2-b]thiophene;
PDPP-C4Ph: poly(3,6-di(2-thien-5-yl)-2,5-di(2-octyldodecyl)-pyrrolo[3,4-c]pyrrole-1,4-dione) with alkylphenyl (C4Ph); PU: polyurethane;
PDPP3T: poly(diketopyrrolopyrrole-terthiophene); CNTs: carbon nanotubes; MoS : molybdenum disulfide; IGZO: indium gallium zinc oxide; ITO:
2
indium tin oxide; ITZO: indium tin zinc oxide.
polyurethane acrylate (PUA)-coated with AgNWs as an electrode and PEDOT:PSS as a hole injection layer
to fabricate a vertically integrated stretchable AMOLEC array. The stretchable emissive layer was fabricated
by mixing the super yellow luminescent polymers, ion conductive polymers, ethoxylated trimethylopropane
triacrylate (ETT-15) and lithium trifluoromethane sulfonate (LiTf). The developed AMOLEC array could
stably operate under variation deformation conditions [Figure 7B].

Organic-based stretchable semiconductors with structural engineering
Another pathway to obtain stretchability in organic-based semiconductor materials is to provide durability
against mechanical stress through the structural engineering of device components. For example, it is
possible to control the crack formation and the stress distribution by inserting an interlayer between the soft
substrate and the semiconductor, or by applying a pattern to the semiconductor film. Li et al. showed a
strategy for soft interlayer designs that can significantly improve the elasticity of the active layers on
substrates which have lower elastic modulus by using relatively high modulus stretchable materials
[Figure 7C] . They designed a soft interlayer structure consisting of SEBS to overcome the large difference
[87]
in moduli across the interface based on the fracture mechanism [88-90] of the film formed on the elastomer
substrate. The soft interlayer has an intermediate Young’s modulus (2.83 MPa) between the semiconductor
films (DPPT-TT, modulus: 19.4 MPa) and the substrate [polyacrylamide (PAAm), modulus: 55 kPa],
providing sufficient adhesion on both sides. The fabricated stretchable OTFTs on the PAAm substrate with
SEBS soft interlayer structure have an effective Young’s modulus of 5.2 kPa, which is 2-3 times softer than
the conventional elastomer-based stretchable device. Also, Kim et al. fabricated polymer semiconductor